Diazotype photographic material



Patented Nov. 28, 1950 UNITEDSTATES PATENT OFFICE DIAZOTYPE PHOT OGRAPHIC MATERIAL Sam Charles Slifkin,Binghamton, and Henry C. Unkauf, Endicott, N. Y., assignors to General Aniline .& Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application December 16, 1946,

Serial No. 716,670

claims.

which :are readily printable .by exposure through ultraeviolet light on various diazotype photographic materials. To produce diazotype prints proin; this rna nner, it is important that the azo dye imagesor designs be highly efficient in the absorption of ultra-violet light employed inthe printing. The eflicacy of such absorption by azo dyes is referred to as'actinic opacity. If the actinic opacity is w the images obtained in the print are of poor definition, contrast, and clarity. Heretofore, in order to obtain diazotypelayers designed to yield azo dye images of high actinic opacity, it was necessaryto employ diazo sensitizers and couplers of relatively high coupling energies'and in relatively high concentrations. Such prior art diazotype compositions, however, exhibited two major defects. First, the relatively high couplingjenergiespf'the most effective dye formersjforthis purpose caused premature coupling tboccur'even 'duringr'elati'vely short storage periods of the sensitized materi'als'.""Second, attempts to overcome the pre-coupling by stabilizing the components'with high concentrations of acidic stabilizing'materials caused a rapid degradation" of the cellulose'fibers composing the base or supportI carryingthe photosensitive layers. This degradation of the cellulosefibers resulted in'arapid loss of physical strength of the papers and particularly exhibited itself by embrittlem'ehtof the paper support. 1

According to our invention, we overcome the drawbacks of the heretofore known procedures by providing a diazotype sensitizing composition monoazo dye. It further makes possible, if desired, the use of more diazo salt without excessively decreasing stability (storage life) by mass action. Thus, according to our invention, it is possible to employ high concentrations of the diazo and coupling components without. occurrence ofexcessivepremature coupling or with out the use of high concentration of acidicstabilizing materials. Cellulosic supports or carriers provided with the light sensitive diazo components of our invention maybe stored over longer periods of time without exhibiting the defects and undesirable features of heretofore employed diazo compounds and couplers.

Another advantage of-our invention is that the solution of the azo components and coupler which We employ may besc'aused by various mechanical methods to deeply penetrate the support, as for example, by allowing a longer time for the solution to penetrate. This gives added opacity to the azo dye image formed. With the compositions heretofore employed, when deep penetration of the compositions was desired, there was a tendency for the stabilizer to separate from the dye components due to preferential'absorp tion by the support, thereby causing increased pre-coupling of the dye components. On the other hand, our compositions containing components of low coupling potential and small amounts of stabilizers, do not produce such an unfavorable result when applied so as to penetrate deeply into the base or support.

According to our invention, we employ as lightsensitive diazo salts, a para-diazo derivative of an N-alkyl or N-alkylol-m-alkyl, m-alkoxy, malkylol, or -m-carboxy aniline in combination with a coupler of the following formula:

in which-the component materials possess inhrently low'coupling energies and require little stabilization 5 by -'acidic substances. "While the actinic opacity-of the azo dye formed from such component materials; would be expected to be less than with the component's heretofore employed-the need'f'o'r' less stabilizing agent and hence reduced alkaline development results in ami a s lofimprored opacit Furthermore, ouryinventionlmakes possible the, use of alargelexcess of a low coupling potential azb component orlcoupler, thus insuringsubstam tially exclusive -formation of the. more. opaque where X may be H, (CHzMCOOI-I, alkyl or alkylol; Y may be H, $0313: or a salt thereof, n is a small integer, such as 1, 2, 3 or l; and Z may be H or a water-solubilizing group obtained by the Mannich reaction, for example, CH2N,V(CH: )2. In Formula .I when X is H, Z or Y are other thanH- Onexposure' and development, diazotype layers prepared from such components ,produce 1 dye ima esof sepia tones which are hi hly absorptive 3 of ultra-violet light. From such azo images or designs there may be then produced through exposure with ultra-violet light prints on various diazotype materials.

In general, the diazo salts which we employ are those from amines of the type which may be represented by the following generic formula:

NH: (II) In the above formula, R1 is preferably H, but both R1 and R2 may be alkyl or alkylol. In the latter case, however, better substantivity results. X is preferably alkyl although it may also be alkoxy, alkylol, or carboxy. More specifically, Rl is hydrogen, methyl, ethyl, or propyl, hydroxyethyl, or hydroxypropyl; R2 is ethyl, propyl, butyl, hydroxyethyl or hydroxypropyl; and X is methyl, ethyl, propyl, methoxy, ethoxy, hydroxyethyl, hydroxypropyl or COOI-I.

The diazo salts can be represented by the following general formula:

In the above formula, R1, R2 and X have the same significance as in Formula II. The diazo radical as employed in the formula and claims stands for a group necessary for the formation of a diazo salt, as for example, diazonium chlorides, carbonates, fluorides and sulfates, and the double salts of diazos with metal halides, such as zinc chloride, boroniluoride, cadmium chloride and tin chloride. The purposes of our invention, however, are not attained by the use of diazo-N-sulfonates, and it is to be understood that the diazo radical does not include groups which form diazo-N-sulfonates. As specific examples of the diazonium compounds, there may be mentioned the para-diazonium chloride of N-hydroxyethyl-m-methyl aniline, the p-diazonium zinc chloride double salt of N-ethyl-N- hydroxyethyl-m-methyl aniline, the p-diazonium chloride of N-hydroxypropyl m-ethyl aniline, and the p-diazonium chloride of N-ethyl m-methyl aniline. Instead of the m-alkyl derivatives of the above specified compounds, there may be employed the corresponding m-alkoxy such as the m-methoxy and m-ethoxy derivatives; or the m-alkylol derivatives such as the m-hydroxyethyl and the m-hydroxypropyl derivatives; or the m-carboxy derivatives such as the COOH derivative.

The diazo derivatives may be prepared by diazotizing the corresponding anilines by the well-known diazotizi'ng procedure. For example, the anilines are dissolved in water containing hydrochloric acid and cooled with ice and diazotized with the addition of a slight excess of sodium nitrite. If desired, the diazonium compound which forms can be isolated as the zinc chloride double salt.

As specific examples of the coupler there may iazo be employed resorcinoll-sulfonic acid, and its water soluble salts, as for example, its ammonium or sodium salts, B-hydroxy phenoxyacetic acid, dimethylaminomethyl resorcinol monomethyl ether, and 3-hydroxyphenoxyethyl alcohol.

In practice, the above-mentioned diazo derivatives and coupling compounds are applied in aqueous solution together with stabilizing compounds to a suitable base or support. The compositions may contain one or more of our diazo derivatives together with one or more of the above-mentioned coupling components and may also have present one or more stabilizing compounds, as for example, thiourea, citric acid, boric acid, tartaric and lactic acid, oxalic acid, phosphoric acid, and the like.

If desired, the diazo derivatives and the coupling compounds may be dissolved in separate solutions and applied in sequence to the base or support to be sensitized. In this case, we preferably incorporate the stabilizers in the diazo salt solution. To the solutions there may be added also, if desired, small amounts of wetting or leveling agents or various organic solvents such as ethyl alcohol, acetone, or glycerol.

The concentrations of the diazo derivative and coupling component may vary within a range of about 1-3 moles of coupler per mole of diazo derivative. By permitting the employment of high concentrations of the coupler, our invention insures formation of the more opaque monoazo dye. It is an advantage of our invention that both the diazo compound and the coupler may be utilized in large concentrations without danger of precoupling. In general, the amount of the acid stabilizer is rather small ranging from about 5% to 8% by weight in solution.

The following examples will serve to illustrate our invention. In each, the diazo compound is in the form of its zinc chloride double salt.

Example 1 The solution is made up of the following in- 1 gredients:

Water cc Citric acid grams 5 Glycerol cc 5 Thiourea grams 5 Zinc chloride do 5 Resorci'nol-l-sulfonic acid, do 4 p-Diazo of N-hydroxyethyl-m-methyl aniline grams 4 The solution is applied, for example, in excess to one side of a well-sized lightweight paper. The excess is removed by a doctor blade and the sensitive layer then formed on. the paper is dried with warm air. After drying, the sensitized paper is exposed to ultra-violet rays through a design. A sepia colored dye image is formed on development in an atmosphere of ammonia. The dye image thus obtained is highly absorptive of ultraviolet light and may be employed as a pattern for producing additional prints on diazotype paper by exposure to ultra-violet light.

Example 2 A sensitizing solution was made up of the following ingredients:

Water cc 100 Citric acid grams 5 Boric acid do 2 Thiourea do 5 Glycerol ..cc- 5 3.-hydroxyphenoxy acetic acid do 3 p-Diazo of N-ethyl N hydroxyethyl mmethyl anilineu-ha grams 4 This solution was employed to impregnate a piece of well-sized, light weight paper and the excess solution was removed, after which the paper was dried. Thedried, sensitized paper was then exposed as in Example 1. A sepia toned dye' image of high actinic opacity was formed.

Example 3 A sensitizing solution was prepared from the following ingredients: a V

Water -l I cc 100 Citric acid Q. grams 5 Thiourea do- 5 Glycerol 5 Zinc chloride grams; 5 Dimethylaminomethyl resorcinol monomethyl ether grams 3 p-Diazo of N-hydroxypropyl-m-methyl aniline grams 4 This solution on application to a paper base, formed a sensitized layer which when exposed and developed as described in the previous examples formed sepia tone dye images which were highly opaque to actinic rays.

Ewample 4 A piece of light weight, well-sized paper was sensitized, exposed and developed as described in the previous example except that the sensitized layer on the paper was formed from the following solution. A sepia azo dye image of high actinic opacity was obtained.

If desired, a small amount of resorcinol ranging from about 0.5-l% may be added to the solutions in order to shade the sepia dye image obtained.

The above examples are merely illustrative of our invention and we have found that other diazo compounds coming under the general Formula III, and other couplers coming under the general Formula I are useful in our process. How ever, we prefer those diazo derivatives where X is an alkyl, R1 is H and R2 is an alkylol since they have the lowest coupling potentials and exhibit greatest substantivity toward the support. Accordingly, we prefer to employ the p-diazo derivatives of a mono-N-alkylol-m-alkyl aniline.

In place of paper as the upport or base for carrying the light-sensitive layers, there may also be employed sheets or films, for example, those prepared from cellulose acetate, cellulose nitrate, regenerated cellulose and the like; cloth or glass. The sensitizing preparations may be applied to the base or support by dipping, spraying, coating, brushing, or by other ways known to those skilled in th art.

The diazotype copying materials herein described exhibit excellent keeping qualities. They can be stored over. long periods without degradation of the paper base or premature couplingof This together with the high stability of the azo components, their low coupling energies and the production of azo dyes. of i 7 high actinic opacity .are among the advantageous I.

the components.

features of our invention.

We claim:

1.1. Aidiazotype photographic material'comprisr ing a. light-sensitive para-diazo compound of the following formula:

into

.where R1 represents a member selected from the group consisting of hydrogen, an alkyl group and an alkylol group; R2 represents a member selected from the group consisting of an alkyl group and an alkylol group; X represents a member selected from the group consisting of an alkyl group, an alkoxy group, an alkylol group, and a carboxy group; and a coupler of the following general formula:

where X represents a member selected from the group consisting of hydrogen, (CH2)nCOOH, alkyl and alkylol groups, n being a small number; Y is selected from the group consisting of hydrogen and -SO3H and a salt thereof; Z is selected from the group consisting of hydrogen and an aminomethyl group and wherein when X is hydrogen at least one of Y and Z is other than hydrogen in the proportion of about 1 to 3 mols of coupler to 1 mol of diazo compound.

2. A diazotype paper having a light-sensitive layer comprising a light-sensitive para-diazo compound of the following formula:

iazo

where R1 represents a member selected from the group consisting of hydrogen, an alkyl group and an alkylol group; R2 represents a member selected from the group consisting of an alkyl group and an alkylol group; X represents a member selected from the group consisting of an alkyl group, an alkoxy group, an alkylol group,

7 and a carboxy group; and a coupler of the following general formula:

ber; 'Y is selected from the'group consisting of hydrogen and SO3H and a salt thereof; Z is selected from the group consisting of hydrogen and an aminomethyl group and wherein when X is hydrogen at least one of Y and Z is other than hydrogen in the proportion of about 1 to 3 mols of coupler to 1 mol of diazo compound.

3. A diazotype paper having a light-sensitive layer comprising para-diazo-N-hydroxyethyl-mmethyl aniline and resorcinoll-sulfonic acid in the molecular proportion of 1:2.

4. A diazotype paper having a light-sensitive layer comprising para-diazo-N-ethyl-N-hydroxyethyl-m-methyl aniline and 3-hydroxy phenoxyacetic acid in the molecular proportion of 1:1.

5. A diazotype paper having a light-sensitive layer comprising para-diazo-N-hydroxypropyl-m- 8, ethylaniline and dimethylaminomethyl'resorcinol monomethyl ether in the molecular proportion- SAM CHARLES SLIFKIN.

HENRY C. UNKAUF.

7 REFERENCES CITED file of this patent:

UNITED STATES PATENTS Number Name Date 1,628,279 Krieger May 10, 1927 1,807,761 Sprongerts June 2, 1931 1,821,306 Hingst Sept. 1,1931 1,989,065 Schmidt et al Jan; 22,1935 2,196,950 Zahn Apr, 9, 1940 2,245,628 Poser June 17, 1941 2,246,425 Poser et a1 June 17, 1941 2,437,868 Glahn et a1 Mar 16, 1948' 

1. A DIAZOTYPE PHOTOGRAPHIC MATERIAL COMPRISING A LIGHT-SENSTITIVE PARA-DIAZO COMPOUND OF THE FOLLOWING FORMULA: 